Object striking implement vibration dramping

ABSTRACT

Vibrations in the tubular handle of an object striking implement such as a hand tool or ball bat are damped by a vibration damper having a support portion positioned in and engaged with the handle. The vibration damper also has a resilient second portion which cushions contact of the damper with the handle wall and which moves inwardly of the handle in a direction generally transverse to a longitudinal axis of the handle.

BACKGROUND OF THE INVENTION AND PRIOR ART

[0001] 1. Field of the Invention

[0002] The present invention relates to damping of vibration of hollowhandle object striking implements such as hammers and other tools, and,more particularly, to sports object striking implements such as bats forbaseball, softball and youth play. Such bats are typically made of ametal outer shell formed of aluminum or titanium alloy or other metals.

[0003] 2. Prior Art

[0004] Systems for damping of vibrations in implements such as metalshell bats include what can be generally referred to as tuned masssystems and cushion mass systems. Tuned mass vibration systems employ amoveable object such as a vibration damping pendulum located in a hollowcavity within the bat or other implement which is sized, positioned andfrequency matched or tuned to swing within the cavity without contactingthe walls of the cavity to effectively damp vibrations incurred when theimplement strikes an object. Cushion mass systems employ elastomeric orfoam cushions positioned within a cavity in the implement whichresiliently come into contact with the walls of the cavity to reduce theamplitude of vibration transferred through the handle of the implementto the user's hand or hands. Since tuned mass vibration damping systemsreact somewhat more slowly than cushion mass systems due to inertia ofthe tuned mass, tuned mass systems are the dampers of choice for dampingsteady state vibration whereas cushion mass dampers are more frequentlyemployed for damping impact induced vibrations.

OBJECT OF THE INVENTION

[0005] The primary objective of the invention is to provide an objectstriking implement with improved vibration damping of the handle.

SUMMARY OF THE INVENTION

[0006] The present invention provides an object striking implementhaving a tubular handle, an object striking portion affixed to saidhandle and a vibration damper having a support portion affixed in saidhandle and a resilient damping portion flexibly connected to the supportportion. The damping portion is arcuately moveable inwardly of saidhandle in a direction generally transverse to a longitudinal axis ofsaid handle and is compressible to cushion contact of the dampingportion with said handle. The damper therefore functions with some ofthe characteristics of both tuned mass and cushion mass damping systems.

[0007] The vibration damper may be made entirely of resilient materialhaving an undistorted shape and a distorted shape which differs from theundistorted shape when the damper is positioned in the handle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a perspective partially cut away view of a firstembodiment of a bat with a vibration damper.

[0009]FIG. 2 is a perspective view of the vibration damper used in theembodiment of FIG. 1 in its undistorted shape.

[0010]FIG. 3 is a perspective view of a stopper used in the bat of FIG.1.

[0011]FIG. 4 is a partial axial cross-section of a second embodiment ofa bat with a vibration damper.

[0012]FIG. 5 is a perspective view of the vibration damper used in theembodiment of FIG. 4 in its undistorted shape.

[0013]FIG. 6 is a partial axial cross-section of a third embodiment of abat with a vibration damper.

[0014]FIG. 7 is a perspective view of the vibration damper used in theembodiment of FIG. 6 in its undistorted shape.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Although the invention pertains generally to dampening ofvibration in the handles of various types of implements used to strikeobjects and thus encompasses hammers, axes and other tools andobject-striking implements, the invention will be primarily describedwith reference to ball bats wherein the invention has particularutility.

[0016] The perspective view of FIG. 1 shows an implement comprising aball bat 10, not to scale, which may be made of metal such as aluminumor titanium, having a tubular handle 12, an object striking portioncomprising a barrel 14 which may be integrally formed with the handle, aknob 20 welded, press fit or otherwise affixed to a proximal end 16 ofthe handle 12 and a barrel end cap 22 press fit, welded or otherwisefirmly affixed to the distal end 18 of the barrel 14. Such bats aretypically made of tubular aluminum, titanium or other metal or of partmetal or may be made of composite construction as is well known in theart. Undesirable vibration is often transmitted to the hand or hands ofthe user when an object is struck, particularly when the object isstruck away from the desired “sweet spot” of the object striking portionof the implement, in this case, whenever a ball is struck other than inthe main portion of the barrel 14. The situation is exacerbated in coldweather and when the object is struck close to or on the handle portionof a bat.

[0017] A resilient vibration damper 30 is shown in FIG. 1 comprised offirst and second elongated members 32, 42 each bent and therebydistorted generally into a U or horseshoe shape when inserted into thehandle 12 of the bat 10. Although two U-shaped vibration damping members32, 42 are shown in this embodiment, a single vibration damperconstructed of resilient material such as an elastomer or syntheticelastomer and which is distorted from its ordinary undistorted shapewhen positioned in the tubular handle 12 of the bat can be used. Oneportion of the damper, in this case the connecting part or bridge orbridges 38, 48 of the U-shape, is positioned in and resiliently engagedwith the interior wall of the handle 12 and the legs 34, 36 of themember 32 (as well as the legs 44, 46 of the member 42, if a secondU-shaped member is employed) extend generally axially of the bat handle12 near or in light contact with the handle wall and are therefore freeto flex when subjected to vibration induced by contact with a ball sothat the legs 44, 46 can vibrate inwardly of the handle wall in adirection transverse to the longitudinal axis of the handle. As will beapparent from viewing the drawings, the support portion of the damper 30which is engaged with the handle 12 is axially spaced from the portionor portions of the damper 30 such as the legs 44, 46 which are free tovibrate transverse to the longitudinal axis of the handle 12.

[0018] Preferably, the resilient elongated members 32, 42 are formed ofa natural or synthetic elastomer such as rubber having a specificgravity of at least 0.75 and preferably 1.0 or higher. The rubbercomposition preferably also is soft having a Shore durometer hardness inthe range from 5 A through 60 D. As seen in FIG. 2, the elongated member32 preferably has an elliptical cross section having a major axis whichequals approximately half of the inner diameter of the handle 12. Themember 32 (and member 42 if used) is distorted when positioned in thehandle 12 such that the legs of the member or members arecircumferentially spaced, preferably equally, in the handle 12.

[0019] Because of the damper 30 is distorted when positioned in thehandle 12, the elastic memory of the damper causes firm engagement ofthe distorted support portion of the damper 30 with the interior wall ofthe handle 12. In this embodiment of the invention, the undistortedlength of the elongated member 32 may be about ten times the major axisof the elliptical cross section; however, other lengths can be used solong as the performance characteristics of the bat are not materiallyaltered.

[0020] A stopper 50, preferably fabricated of urethane plastic orfunctionally equivalent material, and preferably having spaced elongateribs 52 and a hollow interior, may be press fit or adhesively bonded tothe bat shell at a selected location to prevent the damper 30 frommoving beyond its desired position in the handle 12 into the barrel 14of the bat. The damper 30 can be easily distorted and slid into the bathandle 12. The ends of the legs 34, 36, 44, 46 that preferably lightlycontact the handle 12 when the implement is in a static non-vibratingcondition can therefore flex or vibrate inwardly away from the handlewall in a direction transverse to the longitudinal axis of the handle 12upon impact induced vibration. It will be noted from the drawings thatthe members 32, 42 are positioned in the handle to permit movement ofthe legs without contact between the legs of the first member 32 andthose of the second member 42 although minor contact during intensevibration of the damper 30 may in fact take place under severe impactinduced vibration. The size, weight and resiliency of the above damper30 and other dampers to be described herein, may be adjusted asnecessary to effectively damp vibration of expected frequencies in thehandles of the object striking implements with which they are used.

[0021] Laboratory tests of impact induced vibrations in metal shellbaseball bats have demonstrated that significant improvement in dampingvibrations is attainable (tolerable amplitude of vibrations is attainedin less time) using dampers as described above and that the weight ofthe damper itself can be reduced from about 0.43 oz. as used in priordesigns using cushioned bat damping by a factor of about 25% usingdampers as described above having a weight of about 0.3 oz.

[0022] Turning now to the embodiment of the invention seen in FIGS. 4and 5 wherein like reference numerals depict like parts, a singleresilient vibration damper 60 has a first portion 62 preferably ofcylindrical cross-section, which is distorted by radial compression andengaged with the interior wall of the handle 12 to hold the damper indesired position in the handle 12. The portion 62 of the damper 60 maybe glued into the handle 12 to hold the damper 60 in selected position.The damper 60 also includes elongate second and third portions 64, 66each having an end 65, 67 which is preferably in light contact with theinterior wall of the handle when th bat is in a static condition and isfree to flex or vibrate in a direction transverse to the longitudinalaxis of the handle upon impact induced vibrations. Although thisembodiment of damper is not symmetrical as shown in the drawings, i.e.both ends 65 and 67 engage the same side of the handle 12, an axiallysymmetrical form of this embodiment can be fabricated with as few as twoor three equally circumferentially spaced second and third portions 64,66 which extend generally in opposite axial directions from the firstportion 62. The portions 64, 66 are preferably arcuately configured witha radius of curvature which may be approximately equal to the outerdiameter of the handle 12. This ensures that when the damper 60 isproperly positioned in the handle 12, at least one of the portions 64,66 is slightly distorted by contact with the inner wall of the handle 12and both of the ends 65, 67 are permitted to flex inwardly in adirection transverse to the longitudinal axis of the handle 12. It isnot essential that both ends 65, 67 be located in the handle 12 sincethe end 67 closest to the barrel end of the bat may be slightlydisplaced from the inner surface of the bat wall as the radius of thewall gradually enlarges toward the barrel of the bat. Other radii ofcurvature for the arcuate configuration of the portions 64, 66 of thedamper 60 can, of course, be chosen so long as the ends 65, 67resiliently engage the interior wall of the handle 12. The damper 60 ispositioned such that the end 65 located near the proximal end 16 of thehandle 12 does not contact the inner surface of the end cap 20.

[0023] A third exemplary embodiment of the invention is shown in FIGS. 6and 7 wherein the handle 12 includes a taper forming an enlarged portion15 near the proximal end 16 and knob 20. The resilient vibration damper70 in this embodiment preferably has an undistorted shape in the form ofa toroid so that the damper 70, when distorted in position in the handle12, has a first portion 72 which is compressed and resiliently engagedwith the handle and a second portion 74 which is free to vibrate in theenlarged portion 15 of the handle 12 in a direction transverse to thelongitudinal axis of the handle, the first portion 72 being axiallyspaced in the handle from the second portion 74.

[0024] In the embodiments of FIGS. 4-7, like the embodiment of FIGS.1-3, all of which are designed for reducing vibration in bats, thedamper preferably comprises an elastomer or synthetic elastomer having aspecific gravity of not less than 0.75 and preferably 1.0 or above andis formulated to have a Shore durometer hardness in the range from 5 Athrough 60 D.

[0025] Those skilled in the art will understand from the foregoing thatvarious other configurations of vibration dampers can be used inaddition to the embodiments shown and described. For example, dampers ofserpentine, helical or other curved configuration or combinations ofcurved configurations can be used. The damper may be made wholly orpartly of resilient material. Part of the damper engages the interiorwall of the handle of the implement and another axially spaced resilientpart of the damper is positioned to both vibrate within and collide withthe interior wall of the handle resulting in a combination of cushionedand tuned mass damping to dissipate vibration.

[0026] Persons skilled in the art will appreciate that variousmodifications of the invention can be made from the above describedpreferred embodiment and that the scope of protection is limited only bythe following claims.

1. An object striking implement having a tubular handle, an objectstriking portion affixed to said handle and a resilient vibration damperhaving a first portion positioned in and engaged with said handle, saidvibration damper having an undistorted shape and a distorted shape whichdiffers from said undistorted shape when said damper is positioned insaid handle, said damper having a second portion free to vibrateinwardly of said handle in a direction transverse to a longitudinal axisof said handle, said first portion being distorted and axially spacedfrom said second portion.
 2. The implement of claim 1, wherein saiddamper comprises a first elongated member having a distorted shape whichgenerally comprises a U having legs which extend generally parallel to acentral axis of said handle.
 3. The implement of claim 2, wherein saiddamper further comprises a second elongated member having a distortedshape which generally comprises a U having legs which extend generallyparallel to said axis.
 4. The implement of claim 3, wherein said legs ofsaid first elongated member extend toward a handle end of said implementand said legs of said second elongated member are remote from saidhandle end.
 5. The implement of claim 4, wherein at least some of saidlegs contact said handle when said implement is in a static condition.6. The implement of claim 5, wherein said members comprise an elastomeror synthetic elastomer having a specific gravity of not less than 0.75.7. The implement of claim 5, wherein said members comprise an elastomeror synthetic elastomer have a Shore durometer hardness in the range offrom 5 A through 60 D.
 8. The implement of claim 5, wherein said tubularhandle has a substantially constant inner diameter and said members havean undistorted cross-section comprising an ellipse which has a majoraxis which equals approximately half of said inner diameter.
 9. Theimplement of claim 8, wherein said legs are circumferentially spacedfrom each other in said handle.
 10. The implement of claim 9, furthercomprising a stopper positioned in said implement to limit movement ofsaid members axially of said handle.
 11. The implement of claim 10,wherein said stopper is positioned from a proximal end of said handle adistance greater than the axial distorted length of said members. 12.The implement of claim 11, wherein said members are positioned in saidhandle to permit movement of said legs without contact between saidfirst member and said second member.
 13. The implement of claim 12,wherein said implement is a ball bat.
 14. An object striking implementhaving a tubular handle, an object striking portion and a resilientvibration damper having a first portion positioned in and engaged withsaid handle, said vibration damper having an undistorted shape and adistorted shape when said damper is positioned in said handle whichdiffers from said undistorted shape, said damper having elongate secondand third portions each having an end free to flex in a directiontransverse to a longitudinal axis of said handle, said first portionbeing axially positioned between and spaced from said second and saidthird portions.
 15. The implement of claim 14, wherein said firstportion is cylindrical and said second and third portions are arcuateand have at least one end which contacts said handle when said implementis in a static condition.
 16. The implement of claim 15, wherein saidhandle has a substantially constant inner diameter and second and thirdportions have a circular cross-section having a diameter equal to abouthalf said inner diameter of said handle.
 17. The implement of claim 16,wherein said damper comprises an elastomer or synthetic elastomer havinga specific gravity of not less than 0.75.
 18. The implement of claim 16,wherein said damper comprises an elastomer or synthetic elastomer have aShore durometer hardness in the range of from 5 A through 60 D.
 19. Theimplement of claim 18, wherein said implement comprises a ball bat. 20.An object striking implement having a tubular handle having an enlargedportion, an object striking portion affixed to said handle and aresilient vibration damper having a first portion positioned in andengaged with said handle, said vibration damper having an undistortedshape and a distorted shape which, when said damper is positioned insaid handle, differs from said undistorted shape, said damper having asecond portion free to flex in said enlarged portion of said handle in adirection transverse to a longitudinal axis of said handle, said firstportion being axially spaced from said second portion.
 21. The implementof claim 20, wherein said damper has an undistorted shape substantiallycomprising a toroid.
 22. The implement of claim 21, wherein said dampercomprises an elastomer or synthetic elastomer having a specific gravityof not less than 0.75.
 23. The implement of claim 22, wherein saiddamper comprises an elastomer or synthetic elastomer having a Shoredurometer hardness in the range of from 5 A through 60 D.
 24. Theimplement of claim 23, wherein said implement comprises a ball bat. 25.An object striking implement having a tubular handle, an object strikingportion affixed to said handle and a vibration damper having a supportportion affixed in said handle and a resilient damping portion flexiblyconnected to said support portion, said damping portion being arcuatelymoveable inwardly of said handle in a direction generally transverse toa longitudinal axis of said handle, said damping portion beingcompressible to cushion contact of said damping portion with saidhandle.
 26. The implement of claim 25, wherein said damper is madeentirely of resilient material.
 27. The implement of claim 26, whereinsaid vibration damper has an undistorted shape and a distorted shapewhich differs from said undistorted shape when said damper is positionedin said handle.
 28. The implement of claim 27, wherein said dampercomprises a first elongated member having a distorted shape whichgenerally comprises a U having legs which extend generally parallel to acentral axis of said handle.
 29. The implement of claim 28, wherein saiddamper further comprises a second elongated member having a distortedshape which generally comprises a U having legs which extend generallyparallel to said axis.
 30. The implement of claim 29, wherein said legsof said first elongated member extend toward a handle end of saidimplement and said legs of said second elongated member are remote fromsaid handle end.
 31. The implement of claim 30, wherein at least some ofsaid legs contact said handle when said implement is in a staticcondition.
 32. The implement of claim 31, wherein said members comprisean elastomer or synthetic elastomer having a specific gravity of notless than 0.75.
 33. The implement of claim 31, wherein said memberscomprise an elastomer or synthetic elastomer have a Shore durometerhardness in the range of from 5 A through 60 D.
 34. The implement ofclaim 31, wherein said tubular handle has a substantially constant innerdiameter and said members have an undistorted cross-section comprisingan ellipse which has a major axis which equals approximately half ofsaid inner diameter.
 35. The implement of claim 34, wherein said legsare circumferentially spaced from each other in said handle.
 36. Theimplement of claim 35, further comprising a stopper positioned in saidimplement to limit movement of said members axially of said handle. 37.The implement of claim 36, wherein said stopper is positioned from aproximal end of said handle a distance greater than the axial distortedlength of said members.
 38. The implement of claim 37, wherein saidmembers are positioned in said handle to permit movement of said legswithout contact between said first member and said second member. 39.The implement of claim 38, wherein said implement is a ball bat.